I was recently emailed a job offer at university A Doha, which I accepted (via email), assuming it was the best I would be offered. I've since received an invitation to interview with university B, in Doha...my first choice university.
Uni A would like to begin the process of applying for my work visa, a process that will take some time and after which, I will sign an actual contract. So, they will have begun an investment.
My questions is: How much of an obligation do I have to uni A if I begin the visa process? If I interview/accept with uni B (immediately then declining uni A), could there be some backlash (I've read about being "blacklisted" in Saudi)? Could the visa sponsored by uni A be easily cancelled and the process started again with uni B, assuming I'm offered the position?
Oh, morals and ethics!
Any thoughts, experiences or advice would be appreciated.

Normally, if university A has begun the paperwork for the visa with the Ministry, that will block you from a visa at university B. I know this is what happens in Oman and the UAE. So, you would need to decline job A before they start the paperwork.

An interview is NOT a job, often it takes them weeks to decide. So... if you now decline the first job in hope that you get the second, you may end up with none.

This is a "game" better played between jobs in two different countries... not the same one.